Seasonal migration changes
Changes in fall and spring centers of biomass
To narrow down the potential list of species interactions, I’m pulling out a number of species whose distance between their fall and spring centers of biomass have changed significantly (p value <= 0.05). This has narrowed our list of 29 predatory species down to 8. Some have increased their distance between centers and some have decreased. We will classify these species with their movement classifications, examine how prey species are moving, and assess whether those patterns are consistent with the previously hypothesized overlap patterns.
Movement and overlap
Previously, we described the movement patterns of roughly 40 species caught in the NEFSC Bottom Trawl survey. Plotted below, the eight species demonstrating the strongest change in seasonal center of biomass are classified in this method.
Contract: Goosefish
Lean: Scup, Thorny skate, Winter skate
March: Red hake, Silver hake, Smooth dogfish
Expand: Spiny dogfish
In our overlap analysis, we’ve described seven of the eight above species as predators, with silver hake representing prey species, along with alewife, Atlantic herring, longfin squid, and northern sand lance. We compare the trends of species distributions, then describe the expected relationship based on our movement matrix. We will then map the spatial intersection at the decadal time scales to see if hypothesized overlap pattern is consistent with the trawl survey results. It is likely that we will include other environmental variables, such as average depth, sea surface and bottom temperature.
